Series MT+CT - Current transformers

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Current transformers are used extensively for measuring current. This new CT range covers every facility with three-phase and single-phase. Operating from currents from 40A to 4000A.

Function

When current in a circuit is too high to apply directly to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments.

A current transformer isolates the measuring instruments from what may be very high Current in the monitored circuit.

Applications

Current transformers are commonly used in metering.

Features

The CT is typically described by its current ratio from primary to secondary. Often, multiple CTs are installed for various uses. For example, protection devices and revenue metering may use separate CTs to provide isolation between metering and protection circuits, and allows current transformers with different characteristics (accuracy, overload performance) to be used for the devices. The primary circuit is largely unaffected by the insertion of the CT. The rated secondary current is commonly standardized at 5A.

For example, a 4000:5 CT secondary winding will supply an output current of 5 Amperes when the primary winding current is 4000 A.

The load, or burden, of the CT should be a low resistance. The accuracy of a CT is directly related to a number of factors including:

burden

burden class/saturation class

rating factor

load and physical configuration

For the IEC standard, accuracy classes for various types of measurement are set out in IEC 60044-1, Classes 0.5, 1 and 3.

The class designation is an approximate measure of the CTs accuracy.

The ratio (primary to secondary current) error of a Class 1 CT is 1% at rated current; the ratio error of a Class 0.5 CT is 0.5% or less.

Industrial Solutions

Industrial Solutions empowers smarter business operations by connecting equipment, software and services to protect, control and optimize assets within electrical infrastructures. The business provides customers, across various industries, with end-to-end product and service solutions that help ensure the reliability and protection of their electrical infrastructure.